1. Field of the Invention
This invention relates generally to automated mailing systems which include a postage value determining system processor interconnected to a postage scale and various peripheral devices including a postage meter. More particularly, the present invention is directed to a systems interface which facilitates communications between a system processor adapted for communication with subsystem processors along a serial data bus and a peripheral controller interface adapted to communicate with a system processor along parallel lines.
2. Brief Description of the Prior Art
Various devices and systems have been developed to assist in determining the proper postage for mailing articles. Among the simplest was a manually operated scale which provided a visual indication of the article weight. An operator was required to refer to printed postal rate charts and special fee charts employing the weight reading as well as destination and class of service for a determination of the amount of postage to be applied. It should be appreciated that this technique was time consuming and susceptible to many operator introduced errors especially in conjunction with volume mailing operations.
In order to reduce a potential source of human introduced errors, various machines have been proposed. Illustrated in U.S. Pat. No. 3,692,988, issued to Dlugos et al. on Dec. 9, 1972 and assigned to the assignee of the present invention, is a typical example. In this patent, a parcel postage metering system employed both electromechanical and electronic technology to generate postage representing signals as a function of the desired class of service, a zone and a parcel weight input. A system processor calculated the appropriate transportation charges by reference to a look-up table stored in a rate memory.
The development of automated mailing systems led to the independent development of peripheral devices to be employed in conjunction with system processors. For example, meter setting devices have been developed for moving the postage setting levers of postage meters. Such meter setting devices were controlled by individual processors.
Electronic postage meters which did not require meter setting devices were also developed. A typical electronic postage meter was disclosed in U.S. Pat. No. 3,978,457, entitled Microcomputerized Electronic Postage Meter System, issued Aug. 31, 1976 to Frank P. Check, Jr. et al. and also assigned to the assignee of the present invention. Further peripheral devices employed in conjunction with mailing systems included printers, accounting systems, and computer interfaces.
As a result of independent development of various peripheral devices, postage value determining system processors were capable of communication with only selected peripheral devices having a compatible communications protocol. Thus, a potential purchaser of a particular mailing system including a desired scale having a system processor would not be able to select many of the available peripheral devices due to the incompatibility of the communications system employed by the peripherals.